Marie tells of a knight from the legendary King Arthur's court, named Lanval. He is a knight possessed of great qualities including both beauty and valor, and as a result is envied by many other knights who would not have grieved had he suffered misfortune. Such envy is manifest in his standing at court. Arthur never grants him anything (despite Lanval's loyal service) and neither do the other knights make any effort to help him. As he was born far away and has long since spent his inheritance, Lanval lives a sad, lonely life.
One day, Lanval heads out to the country for leisure. When he approaches a stream, his horse grows frightened, so he lets it loose and lies down to revel in his sadness. A while later, he sees two beautiful damsels approaching, one with gold dishes and the other with a towel. He stands to meet them, and they explain that they have come to conduct him to their mistress, who waits in a nearby tent.
Lanval leaves his horse behind and accompanies them to a magnificent tent finely adorned, so fine that great emperors could not "have afforded even the right-hand side of it." Even finer is the lady within, who "surpassed in beauty the lily and the new rose when it appears in summer. She lies half-covered amidst other fine adornments, to which Marie gives much description.
The maiden calls Lanval and tells him she has come in search of him from her deep love, and should he prove himself worthy, she will grant him a happiness without equal. He sees her beauty and is equally struck with love, so much so that he promises he would do whatever she might ask. At his promise, they sleep together and are joined in love. She grants him the boon that he would never wish for anything, and in fact the more he might spend in life, the more he would have to continue spending. He is granted lodging in her tent, food, and wonderful clothing. The only requirement is that he tell nobody about her and their love, or else he will lose her forever. After a long time together, she tells him he must leave, and tells him that anytime he wishes to see her, he merely needs to think of a pure place and she will join him there.
That night, Lanval almost doubts the existence of the lady, but he arrives home to find his men as finely dressed as he is. From that moment onwards, he becomes a model of generosity, giving gifts freely, granting pardon to prisoners, and offering hospitality to all, even as guests cannot determine from where his wealth comes. All the while, he finds joy in visiting with his beloved any time he wants.
Later that year, several knights are relaxing in a garden when Gawain realizes Lanval is not with them and chastises his group for having neglected to include Lanval. Gawain takes a group to fetch Lanval, who comes willingly. Meanwhile, the queen (Guinevere, though she is not named explicitly by Marie) sees Lanval through her window and devises a plan. She dresses in her most magnificent gown and brings several ladies out to the garden with her. The girls are quickly approached by the knights, but Lanval, who has retreated from the crowd to dream of his own lady, is approached by Guinevere. She quickly confesses her desire for him, and offers herself to him. He gently rejects her advances, citing his loyalty to Arthur. Angry, she responds by accusing him of homosexuality, suggesting that his degeneracy has affected Arthur.
Here Lanval makes his mistake. Angered by her petulant accusation, he defends himself as loving and being loved by a woman of such loveliness that even his beloved's serving girls are superior in beauty and goodness to Guinevere. Guinevere flees him, upset, and takes to her room, swearing not to rise until her husband avenges the insult.
When the king returns, his queen complains to him, fallaciously claiming that Lanval had attempted to seduce her and, in response to her refusal, made the claim that his beloved's serving girls were superior to her. In a fury, Arthur swears that unless Lanval can defend himself in court, he will have the knight hanged. He sends barons to fetch Lanval, who meanwhile is in extreme grief, having lost access to his beloved because of his failure to keep the secret. He calls to her over and over, to no avail, and "it was a wonder he did not kill himself."
Lanval is brought to the king, who accuses him of great wrong. Though in enough sorrow to welcome death, Lanval defends himself from the queen's claims of his lechery, though he does admit the truth of his words about his beloved and her attendants. He agrees he will follow whatever decision the king's court finds, and so Arthur calls together his men to advise him. They decide to set a court date so as to assemble a larger jury, but this requires someone to stand bail for Lanval. Because he is an outcast, nobody initially is willing to stand as pledge until Gawain and his men offer to take the burden. Lanval is released, and Gawain's men escort him home, chastising him for giving in to such a foolish love. Over the next days, they keep a close eye on him, fearful he will neglect his health.
The day of the trial comes, and the barons assemble to act as jury. Arthur wishes for a speedy verdict to appease the queen, but the barons are mixed. Some wish to punish him in service of their lord's wishes, while many others feel great pity for this poor man who does not hide his sadness. They decide to offer Lanval the following bargain: since he had pledged the truth of his words, he would be acquitted if his beloved were to step forward and prove his words true, and if she does not, he will be banished. Lanval informs them she will not come to his aid.
On the verge of making their verdict, two pretty maidens approach on palfreys. They are much admired, and Gawain and his knights inform Lanval of their arrival, assuming one of these fine women must be his beloved. However, Lanval has never seen them before. Arthur receives them, and when they ask that a room be prepared in great fashion for their lady, whose arrival is impending, Arthur grants it.
Desperate for quick verdict, Arthur pressures the barons, who inform him their deliberation was interrupted by the arrival of the ladies. They have barely resumed discussion when two more ladies arrive, these even more beautiful and more finely adorned. Marie says that both were more beautiful than Guinevere, but Lanval nevertheless does not recognize them and does not confess to loving either one. They too ask for a chamber to house their arriving lady, which Arthur grants before again pressuring the barons for a quick verdict to appease the queen's impatient anger.
Yet again, the barons are on the cusp of a verdict when a single lady appears, more beautiful than anyone in the world and dressed to match. Marie spends much description on her loveliness, which floors all who witness her arrival. Lanval is informed of her approach, and when he recognizes her as his beloved, swears he no longer cares for his life now that he can see her again.
The lady tells Arthur that Lanval has been wrongly accused and hopes her arrival will save him. The barons speedily attest to the accuracy of Lanval's claim, and he is freed. The lady and her attendants leave immediately despite Arthur's attempts to keep them. On their way out of town, Lanval leaps from a high wall and lands on the lady's palfrey, and the two ride together to Avalon, and are never seen again.
"Lanval" is essentially the story of an outcast, and through its plot Marie explores the theme of great love that cannot exist in conjunction with the real world.
It is first worthwhile to consider how removed Lanval is from his society at the very beginning. Even though he exemplifies chivalrous values – loyalty to his lord, generosity, and valor – he is not accepted. In fact, Arthur, in forgetting to grant Lanval land and wealth, is failing in his own feudal duties (in which the lord also owes the vassal loyalty). As a man from another land, Lanval is a well-drawn picture of a man removed from the world.
So it is no surprise that his great happiness and love would also exist apart. Marie rarely spends such narrative time in the descriptions she accords both the beloved lady and the lady's adornments, which suggests that we are to recognize how otherworldly they are. Her most common rhetorical technique is to praise what the lady has as superior to anything that has been known before, even to great emperors. The sense seems to be that we should identify this lady as magical, almost like a fairy from a realm greater than our own.
There are several elements and symbols that help characterize this idea that Lanval's love is meant to exist apart from society. Firstly, he leaves his horse behind to visit the lady. As a horse is always associated with a knight, this implies that he is willing to forsake the world that makes him an outcast. And he is well-rewarded by the splendid tent and gorgeous woman, whose only request is that he keep their love secret. Lanval takes her wish to heart, and only intensifies his devotion to solitary living, so much so that when Gawain invites him out to take leisure with the other knights, Lanval's first instinct is to go off by himself.
Marie wishes us to realize, however, the tragedy that such an intensely personal love will always be at odds with the world, so dedicated to society of others. Consider how no other characters ever act or are seen alone in the poem. The only other valiant character, Gawain, is nevertheless always described as being part of a company, even when they are nameless, as though to suggest he cannot act without his buddies. Arthur cannot decide Lanval's fate without calling together his men, who then request that they contact more men to facilitate the process.
Indeed, the world is an ugly place, where loyalty is not rewarded, and the cruel lies of the insulted queen can force a trial. It's no wonder that the lady asks that Lanval keep their love secret: such beauty, known only to two lovers, has no place in the ugly world.
From a sexual standpoint, it is useful to think of Lanval's love as a type of masturbation. While Marie suggests the existence of the lady (since through her he is given wealth that others notice), it is equally useful to remember that she is too good to be true, as much fantasy as reality. Lanval spends time alone even when Guinevere brings her courtly ladies to be wooed by the knights, and enjoys a love that can only exist on its own. While Marie does not paint this in a moral light (i.e., masturbation is bad), it is plausible to read one message of the lay as a warning against giving too much credence to our fantasy at the expense of the world that we are necessarily a part of.
The other virtues stressed in the lay are loyalty and justice. In terms of the former, Lanval is praised for having been true to Arthur even as Arthur shows a lapse in duty to him. And further, what does one make of the three levels of revelation that end up with the lady arriving at the end? Perhaps it is a simple reliance on the fairy tale pattern of threes that the lady's arrival is preceded by two sets of attendants, but it could also be seen as a test of Lanval's loyalty. He has already lapsed in revealing the existence of his beloved to Arthur, but here he shows his true affection by not claiming that these other fine ladies are indeed his own. Were he to do so, it is likely he would be found innocent, since the attendants are indeed superior in beauty to the queen. However, he would rather die than betray his beloved in this way, which might be what leads her to save him.
Ultimately, the two are reunited in a happy ending, but it can't take place in the world. Instead, they take off for Avalon, a mystical realm, and he is never again seen. The world's inadequacy is stressed by the lady's refusal to stay in even the finest of Arthur's rooms, which has been ornately decorated specifically for her. Even the best the world has to offer is inadequate.
The lay also spends much time on the details of the court trial which suggests Marie might be giving honor to her audience and their own ways of justice and trials.
Lastly, Marie makes many authorial interjections in this lay to stress the truth of the poem. This works in the same way as in other lays, though it is arguably more frequent here.